Computer power management with converter for changing generated power mode commands for external devices

ABSTRACT

A computer is connected to an external device and outputs a command to the external device to shift the external device to a power saving state. The computer comprises an operating system generating a first power saving command for shifting the external device to a first power saving state when a non-operation time reaches a first time, a driver converting the first power saving command into a second power saving command for shifting the external device to a second power saving state in which power consumption is lower than the first power saving state. The converted second power saving command is output to the external device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2000-034081, filed Feb. 10,2000, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a power saving control function for acomputer such as a personal computer.

Various portable notebook type personal computers capable of operatingby batteries have recently been developed. A computer of this type hasvarious power saving functions in order to prolong the continuousoperation time of the system by a battery as long as possible. One ofthem is a power saving function concerning a display device such as anLCD or CRT.

Standards for the power saving function include the International EnergyStar standard which defines that a computer must comprise a functioncapable of activating the low-power mode and deep sleep mode of adisplay. The low-power mode is the first low-power state which isautomatically activated after the computer does not operate for thefirst predetermined time. The deep sleep mode is the second low-powerstate which is automatically activated when the computer does notoperate for the second predetermined time. According to this standard,the shift time for activating the low-power mode must be set within 30min, and the shift time must be set to activate the deep sleep modewithin 70 min. Further, the total of the shift times to the low-powermode and deep sleep mode must fall within 70 min. Note that the shifttime is changeable by the user.

For example, if the computer does not operate for a predetermined timeor more set by the user, an operating system (to be simply referred toas an OS hereinafter) generates the first operation mode signal forshifting to a standby state (corresponding to the low-power mode) inwhich the screen display is turned off. Further, if the computer doesnot operate for another predetermined time or more set by the user, theOS outputs the second operation mode signal for shifting to a power-offstate (corresponding to the deep sleep mode). The BIOS receives thesemode signals, and controls the display controller to control theoperation state of the display.

In this manner, if a non-operation state continues for a certain time ormore, power consumption is temporarily reduced, and then the display isturned off. In other words, a plurality of stages (two stages in thisexample) of the power saving state are set. If a mouse or keyboard isoperated in either the standby state or power-off state, displayresumes. In a CRT, the time until display resumes is shorter in returnfrom the standby state than in return from the power-off state. For thisreason, when the computer with the CRT does not operate for apredetermined time, it is not immediately set to the power-off state buttemporarily to the standby state.

Some other OSs further divide the standby state into a plurality ofstates, and gradually reduce power consumption through a plurality ofstates.

In general, a so-called server OS having an advanced network-compatiblefunction does not take multistage power saving control, and directlyshifts to the power-off state after the non-operation state continuesfor a predetermined time, i.e., takes only two, power-on and power-offstates.

Most of the OSs of conventional computer systems first output a standbymode signal when a computer does not operate for a predetermined time,and then output a deep sleep mode signal to set the power-off state whenthe computer does not operate for another predetermined time.

However, some users attach importance to the power saving effect morethan the time-shortening effect until display resumes, do not requirethe multistage power saving state, do not desire to set the power-offstate after the standby state is temporarily set, but desire to directlyset the power-off state. When an LCD is used in place of a CRT, the timeuntil display resumes is almost the same between return from thepower-off state and return from the standby state.

In this manner, most of conventional OSs cannot cope with a demand fordirectly setting the power-off state when the computer does not operatefor a predetermined time, in order to enhance the power saving effect.

Along with upgrading (function advance) of an OS, the upgraded versionof the above-mentioned OS (if the non-operation state continues for apredetermined time, the OS first outputs a low-power mode signal, and ifthe non-operation state further continues, outputs a deep sleep modesignal) can be used as a server OS. When the server OS, whichimmediately shifts to the power-off state in non-operation, is upgraded,the display device of a client is not immediately set to the power-offstate but is temporarily set to the standby state. A client user whodoes not know the change of the OS or forgets it may mistake this statefor a malfunction of the computer, and may be confused. Even a user whoknows the change of the OS may feel unnatural if display operationchanges.

BRIEF SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide acomputer and power saving control method capable of realizing powersaving control in a smaller number of stages or simple power savingcontrol in only two ON and OFF states, and enhancing the power savingeffect with a simple arrangement without changing the OS even if the OSdefines power saving control in a plurality of stages.

It is another object of the present invention to provide a computer andpower saving control method capable of performing power saving controlsimilar to a previous OS without causing confusion or unnatural feelingof the user even if the OS is changed to change computer operationconcerning power saving control.

According to the present invention, there is provided a computer whichis capable of being connected to an external device and outputting acommand to the external device to shift the external device to a powersaving state, the computer comprising a generator configured to generatea first power saving command for shifting the external device to a firstpower saving state when a non-operation time reaches a first time, aconverter configured to convert the first power saving command into asecond power saving command for shifting the external device to a secondpower saving state in which power consumption is lower than the firstpower saving state, and an output unit configured to output the secondpower saving command to the external device.

According to the present invention, there is provided a power savingmethod for a computer which is capable of being connected to an externaldevice and outputting a command to the external device to shift theexternal device to a power saving state, the method comprising detectinga non-operation time; generating a first power saving command forshifting the external device to a first power saving state when thenon-operation time reaches a first time; and converting the first powersaving command into a second power saving command for shifting theexternal device to a second power saving state in which powerconsumption is lower than the first power saving state; and outputtingthe second power saving command to the external device.

According to the present invention, there is provided a computer programfor a computer which is capable of being connected to an external deviceand outputting a command to the external device to shift the externaldevice to a power saving state, the program being stored in a computerreadable medium, and the program comprising the following steps ofgenerating a first power saving command for shifting the external deviceto a first power saving state when a non-operation time reaches a firsttime; converting the first power saving command into a second powersaving command for shifting the external device to a second power savingstate in which power consumption is lower than the first power savingstate; and outputting the second power saving command to the externaldevice.

According to the present invention, there is provided another computerin which an operating system sequentially outputs a plurality of powersaving commands to a hardware to reduce power consumption stepwise, thecomputer comprising a download unit located between the operating systemand the hardware and configured to download a software for receiving theplurality of power saving commands, converting the plurality of powersaving commands into a smaller number of power saving commands, andoutputting the smaller number of power saving commands, and wherein theplurality of power saving commands output by the operating system aresupplied to the hardware as the smaller number of power saving commandsvia the software, and power consumption is reduced based on the smallernumber of power saving commands in a smaller number of stages thanstages defined by the operating system.

According to the present invention, there is provided a still furtherpower saving setting method comprising downloading an operating system;downloading a software for, if the operating system is able to generatea plurality of power saving commands and generates a predetermined powersaving command, for changing the predetermined power saving command intoa power saving command other than the predetermined power savingcommands; and performing a power saving control for a peripheral devicein accordance with the power saving command output from the operatingsystem or the software.

According to the present invention, there is provided a still furthercomputer comprising a download unit configured to download an operatingsystem; a download unit configured to, if the operating system is ableto generate a plurality of power saving commands and generates apredetermined power saving command, download a software for changing thepredetermined power saving command into a power saving command otherthan the predetermined power saving commands; and a power savingcontroller configured to perform a power saving control for a peripheraldevice in accordance with the power saving command output from theoperating system or the software.

According to the present invention, there is provided a still furthermethod of manufacturing a computer, comprising manufacturing a computerfor an order not including an operating system;

manufacturing a software used in the computer to, if the operatingsystem is able to generate a plurality of power saving commands andgenerates a predetermined power saving command, change the predeterminedpower saving command into a power saving command other than thepredetermined power saving commands; and packaging the computer and thesoftware.

Additional objects and advantages of the present invention will be setforth in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the present invention.

The objects and advantages of the present invention may be realized andobtained by means of the instrumentalities and combinations particularlypointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe present invention and, together with the general description givenabove and the detailed description of the preferred embodiments givenbelow, serve to explain the principles of the present invention inwhich:

FIG. 1 is a block diagram showing the arrangement of a computeraccording to the first embodiment of the present invention;

FIG. 2 is a block diagram showing the hierarchical structure of thesystem of the computer according to the first embodiment;

FIG. 3 is a view showing the operation of a driver according to thefirst embodiment;

FIG. 4 is a timing chart for explaining a power saving control accordingto the first embodiment;

FIG. 5 is a timing chart for explaining a power saving control accordingto the second embodiment;

FIG. 6 is a timing chart for explaining a power saving control accordingto the third embodiment; and

FIG. 7 is a flow chart showing the operation of a computer manufacturingsystem by a computer according to the fourth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of a computer according to the present inventionwill now be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the hardware arrangement of a computeraccording to the first embodiment of the present invention.

The first embodiment will exemplify a battery-drivable notebook orlaptop type portable computer, but the present invention can also beapplied to a desktop type computer. The display device is not limited toa liquid crystal display device integrated with the main body, but maybe a separate liquid crystal display device or CRT display device.

A processor bus 1, internal PCI bus 2, internal ISA bus 3, and I²C bus 4are formed on the system board of the portable computer. If necessary,the user connects a docking station serving as an expansion unit forexpanding a function to a docking connector 10 attached to the computermain body. The docking connector 10 has three connector elements 101,102, and 103.

The computer main body incorporates a CPU 11, host/PCI bridge 12, systemmemory 13, display controller 14, DSP interface gate array (DSP I/F GA)15, internal PCI/ISA bridge 16, card controller 17, PCI/DS (DS: DockingStation) bridge 18, BIOS memory (ROM) 19, hard disk drive (HDD) 20,keyboard controller 21, real-time clock (RTC) 22, I/O control gate array23, and power supply controller (PSC) 24.

The functions and arrangements of the components in the computer mainbody in FIG. 1 will be explained.

The CPU 11 executes and controls various application programs includingan OS and utility programs stored in the system memory 13. The processorbus 1 directly coupled to the I/O pin of the CPU 11 has a data bus witha predetermined bit width.

The system memory 13 is a memory device which stores the OS, devicedrivers, application programs to be executed, and processing data, andis formed of a plurality of DRAM modules. The system memory 13 isconnected to the host/PCI bridge 12 via a dedicated memory bus having adata bus with a predetermined width. The data bus of the memory bus canbe the data bus of the processor bus 1. In this case, the memory bus isformed of an address bus and various memory control signal lines.

The host/PCI bridge 12 is a bridge LSI connecting the processor bus 1and internal PCI bus 2, and functions as one of bus masters of theinternal PCI bus 2. The host/PCI bridge 12 has a function ofbidirectionally converting a bus cycle including data and an addressbetween the processor bus 1 and the internal PCI bus 2, and a functionof access-controlling the memory 13 via the memory bus.

The internal PCI bus 2 is a clocked I/O bus. All cycles on the internalPCI bus 2 are synchronized with PCI bus clocks. The PCI bus 2 has anaddress/data bus used by time division.

The data transfer cycle on the PCI bus 2 is formed of an address phaseand one or more subsequent data phases. An address and transfer type areoutput in the address phase, and, for example, 8-, 16-, 24-, or 32-bitdata is output in the data phase.

The display controller 14 is one of bus masters of the internal PCI bus2, similar to the host/PCI bridge 12, and displays image data of a videomemory (VRAM) 143 on a display device such as an LCD 141 or CRT 142. Thedisplay device may be integrated with the main body, or separated. Thecomputer system of the first embodiment has a function of stopping adisplay timing control signal, supplied to the LCD 141 or CRT 142, inaccordance with a request.

More specifically, when a time during which no operation (pointing witha mouse or key input) is done reaches the first time set by the user,the OS outputs the first control signal (power saving request) forshifting the display device to a standby state. When the non-operationtime reaches the second time longer than the first time, the OS outputsthe second control signal for shifting the display device to a suspendstate. Further, when the non-operation time reaches the third timelonger than the second time, the OS outputs the third control signal forshifting the display device to a power-off state. In this case, thedisplay is stopped in both the standby and suspend states, but powerconsumption is lower in the suspend state. For example, the display canbe stopped by stopping generation of either of vertical and horizontalsync signals VSYNC and HSYNC. In the power-off state, the two signalsare stopped. In the standby state, generation of VSYNC is stopped. Inthe suspend state, generation of HSYNC is stopped to realize lower powerconsumption than in the standby state. Note that definition of thestandby, suspend, and power-off states is not limited to this, and maybe realized by stopping another signal.

The BIOS receives the first, second, and third signals from the OS, andtransfers them to the display controller 14.

The DSP interface gate array 15 is one of PCI devices, and constitutes aDSP system for performing various sound processes and telephone/datacommunication processes together with a DSP 151, modem CODEC 152, andsound CODEC 153.

The DSP interface gate array 15 communicates with the DSP 151, modemCODEC 152, and sound CODEC 153 to control sound processing andcommunication processing using the digital signal processing function ofthe DSP 151 under the control of a dedicated device driver programexecuted after being loaded to the system memory 13.

The internal PCI/ISA bridge 16 is a bridge LSI connecting the internalPCI bus 2 and internal ISA bus 3, and functions as one of PCI devices.The internal PCI/ISA bridge 16 incorporates a PCI bus arbiter, DMAcontroller, and the like. The internal ISA bus 3 is connected to theBIOS memory 19, HDD 20, keyboard controller 21, RTC 22, and I/O controlgate array 23.

The card controller 17 is one of PCI devices, and controls a PCMCIA or aPC card having card bus specifications.

The PCI/DS bridge 18 controls connection/disconnection of a bus with thedocking station. That is, the PCI/DS bridge 18 is a bridge LSIconnecting the internal PCI bus 2 and a docking bus 7 corresponding to aPCI bus, and functions as one of PCI devices. The docking bus 7 isexternally led via the connector element 101 of the docking connector10, and connected to the docking station.

The BIOS memory 19 stores a BIOS, and is formed of a flash memory so asto be programmable. In this embodiment, when the BIOS receives a displaydevice power saving request from the OS, the BIOS executes power savingcontrol so as to request the display controller 14 to stop a displaytiming control signal.

The real-time clock (RTC) 22 is a timepiece module having its ownoperation battery, and has a memory which always receives power from thebattery. This memory is used to save, e.g., environment settinginformation representing a system operation environment.

The I/O control gate array 23 is a bridge LSI connecting the internalISA bus 3 and I²C bus 4, and incorporates a plurality of registersreadable/writable by the CPU 11. Using these registers allowscommunicating the CPU 11 with the power supply controller 24 on the I²Cbus 4.

A plurality of control signal lines connected to the docking station areexternally led from the I/O control gate array 23 via the connectorelement 102 of the docking connector 10. The I/O control gate array 23detects docking/undocking between the computer main body and a dockingstation. Further, when the docking station is docked while the computeris powered, the I/O control gate array 23 controls to preventdestruction of the expansion unit in the docking station or malfunctionof the system due to insertion/removal of a hot line.

The I²C bus 4 is a bidrectional bus made of one clock signal line andone data line (SDA), and is externally led via the connector element 103of the docking connector 10.

The power supply controller 24 turns on/off the computer in accordancewith ON/OFF operation of the power supply switch or ON/OFF operation ofan eject switch (described below). In addition, the power supplycontroller 24 controls the power supply in accordance withdocking/undocking of the docking station.

FIG. 2 shows the hierarchical structure of the computer system. An OS204 comprises a timer 206 connected to an input device 202 such as akeyboard or mouse, and detects the non-operation time of the inputdevice 202. If the non-operation time detected by the timer 206 reachesthe first time, the OS 204 outputs the first control signal for shiftingthe display device to the standby state. If the non-operation timereaches the second time longer than the first time, the OS 204 outputsthe second control signal for shifting the display device to the suspendstate. Then, when the non-operation time reaches the third time longerthan the second time, the OS 204 outputs the third control signal forshifting the display device to the power-off state. Before detecting thenon-operation time of the input device 202, the OS 204 outputs a controlsignal for setting the power-on state.

In the present embodiment, a driver 208 is arranged between the OS 204and a BIOS 210. The driver 208 appropriately converts a control signaloutput from the OS 204 into one as shown in FIG. 3, and outputs theconverted signal in order to change the power saving control mode of theOS 204. That is, the driver 208 directly outputs ON and OFF signals forshifting to the power-on and power-off states, while converting standbyand suspend signals for shifting to the standby and suspend states intoOFF signals, and then outputting the OFF signals. In this manner, thedriver 208 converts control signals (standby, suspend, and power-offsignals) for setting a plurality of power saving states generated by theOS 204 into a control signal (in this case, an OFF signal) for setting asingle power saving state. The driver 208 is not originally installed inthe computer, but is downloaded via a network or read from a floppydrive (FD) or CD-ROM driver (neither is shown), and stored in the HDD 20in accordance with a user's demand. The demand is to change the powersaving control mode defined by the OS 204.

A control signal output from the driver 208 is input to the BIOS 210,and transferred to a display controller 212, similar to a control signaloutput from a conventional OS.

An example of power saving control according to the first embodimentwill be explained. FIG. 4 shows the difference in operation between theprior art not including the driver 208 and the present inventionincluding the driver 208.

The OS of this embodiment allows the user to set the shift time to thepower saving state. Thus, the user sets a standby time t1, suspend timet2, and power-off time t3 until the display device shifts from thenon-operation state to the standby state, suspend state, and power-offstate. As will be described below, setting of the suspend time t2 andpower-off time t3 is insignificant, but the user must set them becausethe OS 204 requests setting. When the input device 202 does not operate,the timer 206 starts measuring the non-operation time. When the measuredtime reaches the standby time t1, suspend time t2, or power-off time t3,the OS 204 outputs a standby, suspend, or power-off signal to the BIOS210.

In the prior art, these signals are directly supplied from the BIOS 210to the display controller 212. As a result, if the non-operation stateof the input device 202 continues, the power consumption state of thedisplay device sequentially changes from a normal state to the standbystate, suspend state, and finally power-off state, and the powerconsumption amount gradually decreases.

To the contrary, in the first embodiment, as shown in FIG. 3, all thestandby, suspend, and power-off signals output from the OS 204 areconverted by the driver 208 into power-off signals, which are thensupplied to the BIOS 210. When the non-operation state of the inputdevice 202 reaches the standby time t1, the power consumption state ofthe display device changes from the normal state to the power-off state,as represented by the solid line in FIG. 4. This can reduce powerconsumption by an amount represented by hatched lines in comparison withthe prior art.

Note that when the OS 204 detects the operation of the input device 202after the standby time t1 (power-off state), it requests display devicepower saving cancel, i.e., outputs an ON signal. This ON signal issupplied to the display controller 212 as it is via the driver 208 andBIOS 210. Then, the display device resumes display.

According to the first embodiment, a multistage power saving controldefined by the OS can be easily changed to a simple control using onlytwo states ON and OFF by only installing the driver 208 on the user sidewithout changing an OS or BIOS. This can meet a user's demand forfurther reducing power consumption instead of further shortening thetime from the power-off state to the normal state (display resume).Saving power consumption is very important in a portable notebook typepersonal computer, and even in the use of an AC power supply, is alsoimportant in terms of protection of the global environment.

Other embodiments of the computer according to the present inventionwill be described. The same portions as those of the first embodimentwill be indicated in the same reference numerals and their detaileddescription will be omitted. The above-described OS gradually reducespower consumption from the display state through the standby and suspendstates. An embodiment concerning an OS which takes another reductionform will be explained.

When the input device does not operate, and the non-operation timereaches the first setting time t1, second time t2, or third time t3, anOS of the second embodiment outputs a suspend, power-on, or power-offsignal to an BIOS, as shown in FIG. 5. Note that the second and thirdtimes t2 and t3 cannot be set by the user, and their interval (t3−t2) isvery short. Before the power supply is turned off, it is temporarilyturned on in consideration of the serving life of a display device. Adriver in this case is the same as the driver of the first embodimentshown in FIG. 3 except that input of a standby signal (and output of acorresponding power-off signal) is omitted, and thus is not illustrated.

Without a driver, if the non-operation state of the input devicecontinues for the first time t1 set by the user, the display deviceshifts to the suspend state. Upon the lapse of a predetermined time, thedisplay device is turned on instantaneously and then off. In the secondembodiment, however, a suspend signal output from the OS is converted bythe driver into a power-off signal, which is then supplied to the BIOS.If the non-operation time of the input device reaches the suspend timet1, the display device is turned off. Upon the lapse of a predeterminedtime, the display device is similarly turned on instantaneously and thenoff. For this reason, the second embodiment can save power which wasconsumed in the suspend state from the suspend time t1 to the power-ontime t2 in the prior art.

FIG. 6 shows another embodiment. When the input device does not operate,and the non-operation time reaches the first setting time t1, or secondsetting time t2, an OS of the third embodiment outputs a suspend orpower-off signal to an BIOS, as shown in FIG. 6. A driver in this caseis the same as the driver of the first embodiment shown in FIG. 3 exceptthat input of a suspend signal (and output of a corresponding power-offsignal) is omitted, and thus is not illustrated. Without a driver, ifthe non-operation state of the input device continues for the first timet1 set by the user, the display device shifts to the standby state. Uponthe lapse of the second time t2, the display device is turned off. Inthe third embodiment, however, a standby signal output from the OS isconverted by the driver into a power-off signal, which is then suppliedto the BIOS. If the non-operation time of the input device reaches thestandby time t1, the power consumption state of the display deviceshifts to the power-off state. The third embodiment can save power inthe standby state which was consumed between the power-off time t2 andthe standby time t1 in the prior art.

A computer manufacturing system by a computer for manufacturing acomputer including the above-mentioned driver will be explained as thefourth embodiment. FIG. 7 is a flow chart showing the manufacturingflow.

If the manufacturing system receives a user's order in step S12, thesystem determines in step S14 whether the contents of the orderrepresent attachment of an OS. This is because the user may desire toseparately purchase an OS or may have already had one. If YES in stepS14, the system instructs in step S16 the manufacturing department tomanufacture an OS, driver software corresponding to the OS (e.g., one ofthe first, second, and third embodiments), and computer. In step S18,the computer and driver software corresponding to the OS aremanufactured. In step S20, the OS is installed in the manufacturedcomputer or stored in an FD (or CD-ROM). In step S22, the driversoftware corresponding to the OS is stored in an FD (or CD-ROM). Thecomputer, OS, and driver software FD (or CD-ROM) are packaged togetherin step S24, and shipped in step S26.

If NO in step S14, the system instructs in step S28 the manufacturingdepartment to manufacture driver software (in this case, an OS isunknown, so that general-purpose driver software which can be applied toall currently available OSs, i.e., operates as all the first, second,and third embodiments is preferable) and computer. In step S30, thecomputer and driver software are manufactured. In step S32, the driversoftware is stored in an FD (or CD-ROM). The computer and driversoftware FD (or CD-ROM) are packaged together in step S34, and shippedin step S26.

The fourth embodiment changes the type of driver to be packageddepending on whether a purchase request includes attachment of an OS,and thus can eliminate wasteful packaging of driver software compatibleto all computers.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the present invention in its broaderaspects is not limited to the specific details, representative devices,and illustrated examples shown and described herein. Accordingly,various modifications may be made without departing from the spirit orscope of the general inventive concept as defined by the appended claimsand their equivalents. For example, the device subjected to power savingcontrol is a display device. However, the present invention is notlimited to this, and can also be applied to a storage device such as ahard disk drive or DVD.

The power saving signal output by the driver upon conversion is notlimited to a control signal for setting the minimum power saving state,and may be a control signal for setting a desired power saving state.This is effective particularly in preventing confusion or unnaturalfeeling after computer operation changes along with change (update) ofthe OS, like a recent network server. In this case, the driver sufficesto realize the same state as the state of a control signal output from aprevious OS, and the power saving state need not be limited to theminimum one.

In the above description, the driver is inserted between the OS and theBIOS, power saving signals in a plurality of stages output from the OSare substantially converted into power saving signals in a smallernumber of stages, and the converted signals are supplied to the BIOS.When the user can rewrite the BIOS, like a computer manufacturer, theBIOS may comprise the conversion function instead of using the driver.

The present invention provides a computer and power saving controlmethod capable of realizing power saving control in a smaller number ofstages or simple power saving control in only two ON and OFF states, andenhancing the power saving effect with a simple arrangement withoutchanging the OS even if the OS defines power saving control in aplurality of stages. The present invention provides a computer and powersaving control method capable of performing power saving control similarto a previous OS without causing confusion or unnatural feeling of theuser even if the OS is changed to change computer operation concerningpower saving control.

What is claimed is:
 1. A computer which is capable of being connected toan external device and outputting a power saving command to the externaldevice to shift the external device to a power saving state, thecomputer comprising: a generator configured the generate a first powersaving command for shifting the external device to a first power savingstate when a non-operation time reaches a first time; a converterconfigured the convert the first power saving command generated by thegenerator into a second power saving command for shifting the externaldevice to a second power saving state in which power consumption islower than the first power saving state; and an output unit configure tooutput the second power saving command to the external device instead ofthe first power saving command.
 2. The computer according to claim 1,wherein when a non-operation time reaches a second time longer than thefirst time, said generator generates the second power saving command forshifting the external device from the first power saving state to thesecond power saving state, and said converter outputs the second powersaving command when the second power saving command is input.
 3. Thecomputer according to claim 1, wherein when a non-operation time reachesa second time longer than the first time, said generator generates thesecond power saving command for shifting the external device from thefirst power saving state to the second power saving state, and saidconverter converts one of the first and second power saving commandsinto the other one of the first and second power saving commands, andoutputs the converted command.
 4. The computer according to claim 1,wherein said generator is included in an operating system.
 5. Thecomputer according to claim 1, further comprising an input device, andwherein said generator comprises a detector configured to detect anon-operation time of said input device.
 6. The computer according toclaim 1, wherein the external device comprises a display device.
 7. Apower saving method for a computer which is capable of being connectedto an external device and outputting a power saving command to theexternal device to shift the external device to a power saving state,the method comprising: detecting a non-operation time; generating afirst power saving command for shifting the external device to a firstpower saving state when the non-operation time reaches a first time;converting the first power saving command into a second power savingcommand for shifting the external device to a second power saving statein which power consumption is lower than the first power saving state;and outputting the second power saving command to the external deviceinstead of the first power saving command.
 8. The method according toclaim 7, further comprising: generating the second power saving commandfor shifting the external device from the first power saving state tothe second power saving state, when a non-operation time reaches asecond time longer than the first time; and outputting the second powersaving command when the second power saving command is input.
 9. Themethod according to claim 7, further comprising: generating the secondpower saving command for shifting the external device from the firstpower saving state to the second power saving state, when anon-operation time reaches a second time longer than the first time; andconverting one of the first and second power saving commands into theother one of the first and second power saving commands.
 10. A computerprogram for a computer which is capable of being connected to anexternal device and outputting a power saving command to the externaldevice to shift the external device to a power saving state, the programbeing stored in a computer readable medium, and the program comprisingthe following steps of: generating a first power saving command forshifting the external device to a first power saving state when anon-operation time reaches a first time; converting the first powersaving command into a second power saving command for shifting theexternal device to a second power saving state in which powerconsumption is lower than the first power saving state; and outputtingthe second power saving command to the external device instead of thefirst power saving command.
 11. A computer which is capable of beingconnected to an external device and outputting a power saving command tothe external device to shift the external device to a power savingstate, the computer comprising: a receiver configured to receive a firstpower saving command for shifting the external device to a first powersaving state when a non-operation time reaches a first time; a converterconfigured to convert the first power saving command into a second powersaving command for shifting the external device to a second power savingstate in which power consumption is lower than the first power savingstate; and an output unit configured to output the second power savingcommand to the external device instead of the first power savingcommand.
 12. The computer according to claim 1, wherein the second powersaving command comprises a power off command.
 13. The power savingmethod according to claim 7, wherein the second power saving commandcomprise a power off command.
 14. The computer program according toclaim 10, wherein the second power saving command comprises a power offcommand.
 15. The computer according to claim 11, wherein the secondpower saving command comprises a power off command.